Two-step sealing of anodized aluminum coatings

Abstract

A method includes providing a workpiece with at least one surface having an anodized aluminum coating and a trivalent chromium sealant. The at least one surface of the workpiece is submerged in a post-treatment sealant solution for 0.5 to 20 minutes. The sealant composition consists essentially of a corrosion inhibitor, an organic complexing agent, and an oxidant.

1 . A sealant composition consisting essentially of:
 a corrosion inhibitor;   an organic complexing agent;   an oxidant; and   water.   
     
     
         2 . The composition of  claim 1 , wherein the corrosion inhibitor is selected from a group consisting of: a molybdate compound, a silicate compound, a vanadate compound, a Rare earth salt, a phosphate or orthophosphate compound, a phosphate or orthophosphate silicate compound, a phosphate or orthophosphate silicate hydrate compound, a phosphate or orthophosphate silicate hydrate compound that includes at least one of zinc, calcium, strontium, and aluminum cations, and combinations thereof. 
     
     
         3 . The composition of  claim 2 , wherein the organic complexing agent is selected from a group consisting of: a poly-amine compound, a polyol compound, a poly-thiol compound, and combinations thereof. 
     
     
         4 . The composition of  claim 3 , wherein the organic complexing agent is selected from a group consisting of: a phytate, an EDTA, a thiourea, a benzotriazole, nitrilotriacetic acid, citric acid, a polycarboxylic acid, and combinations thereof. 
     
     
         5 . The composition of  claim 3 , wherein the oxidant is selected from a group consisting of: a permanganate, a peroxide, a persulfate, a percarbonate, a perborate, and combinations thereof. 
     
     
         6 . The composition of  claim 1 , wherein a concentration of at least one of the corrosion inhibitor, the organic complexing agent, and the oxidant is in a range of 1-50 mM. 
     
     
         7 . The composition of  claim 1 , wherein a pH of the composition is between 3 and 9. 
     
     
         8 . The composition of  claim 7 , wherein the pH of the composition is between 4 and 6. 
     
     
         9 . A method comprising:
 providing a workpiece with at least one surface having an anodized aluminum coating and a trivalent chromium sealant;   submerging the at least one surface of the workpiece in a post-treatment sealing solution for 0.5 to 20 minutes, the sealing solution comprising:
 a corrosion inhibitor; 
 an organic complexing agent; 
 an oxidant; and 
 water. 
   
     
     
         10 . The method of  claim 9 , wherein the corrosion inhibitor is selected from a group consisting of: a molybdate compound, a silicate compound, a vanadate compound, a rare earth salt, a phosphate or orthophosphate compound, a phosphate or orthophosphate silicate compound, a phosphate or orthophosphate silicate hydrate compound, a phosphate or orthophosphate silicate hydrate compound that includes at least one of zinc, calcium, strontium, and aluminum cations, and combinations thereof. 
     
     
         11 . The method of  claim 10 , wherein the organic complexing agent is selected from a group consisting of: a poly-amine compound, a polyol compound, a poly-thiol compound, and combinations thereof. 
     
     
         12 . The method of  claim 11 , wherein the organic complexing agent is selected from a group consisting of: a phytate, an EDTA, a thiourea, a benzotriazole, a nitrilotriacetic acid, a citric acid, a polycarboxylic acid, and combinations thereof. 
     
     
         13 . The method of  claim 11 , wherein the oxidant is selected from a group consisting of: a permanganate, a peroxide, a persulfate, a percarbonate, a perborate, and combinations thereof. 
     
     
         14 . The method of  claim 9 , further comprising:
 maintaining a concentration of one or more of the components in a range of 1 to 50 mM.   
     
     
         15 . The method of  claim 9 , further comprising:
 maintaining a solution pH in a range between 3 and 9.   
     
     
         16 . The method of  claim 9 , further comprising:
 maintaining a process temperature in a range of 20° C. to 80° C.   
     
     
         17 . The method of  claim 9 , wherein the sealant composition further comprises a surfactant. 
     
     
         18 . A sealant composition consisting essentially of:
 a corrosion inhibitor;   an organic complexing agent;   an oxidant;   a surfactant; and   water.   
     
     
         19 . The composition of  claim 18 , wherein:
 the corrosion inhibitor is selected from a group consisting of: a molybdate compound, a silicate compound, a vanadate compound, a rare earth salt, a phosphate or orthophosphate compound, a phosphate or orthophosphate silicate compound, a phosphate or orthophosphate silicate hydrate compound, a phosphate or orthophosphate silicate hydrate compound that includes at least one of zinc, calcium, strontium, and aluminum cations, and combinations thereof;   the organic complexing agent is selected from a group consisting of: a poly-amine compound, a polyol compound, a poly-thiol compound, and combinations thereof; and   the oxidant is selected from a group consisting of: a permanganate, a peroxide, a persulfate, a percarbonate, a perborate, and combinations thereof.   
     
     
         20 . The composition of  claim 9 , wherein:
 a concentration of at least one of the corrosion inhibitor, the organic complexing agent, and the oxidant is in a range of 1 to 50 mM; and   a solution pH is in a range between 3 and 9.